Recovering copper from concentrates with insoluble sulfate forming leach

Abstract

This invention provides a novel and an improved hydrometallurgical method for recovering copper values from copper concentrates. The method essentially comprises the following steps:

We claim: 
     
       1. A hydrometallurgical method of recovering copper values from copper sulphide concentrates which comprises: a. forming an aqueous leach solution containing chloride or bromide ions therein and a total amount of acid such that the molar ratio of H +/Cu  is between 0 and about 0.65/1;   b. dispersing copper sulphide concentrates in said leach solution to form a slurry;   c. adjusting the amount of chloride or bromide ions in the slurry such that the molar ratio of Cl -/Cu  or Br -/Cu  is greater than about 0.08/1;   d. carrying out the leaching operation at a temperature between about 115° C. and about 160° C. and under an oxygen pressure above 100 psig, while agitating the slurry;   e. separating resulting leach residue containing the copper values essentially in the form of basic copper sulphate from the leach solution; and   f. recovering the copper values from the leach residue.   
     
     
       2. Method according to claim 1, wherein the aqueous leach solution containing chloride ions is formed with hydrochloric acid. 
     
     
       3. Method according to claim 1, wherein the aqueous leach solution containing chloride ions is formed with NaCl, CaCl 2  or NH 4  Cl. 
     
     
       4. Method according to claim 1, wherein the aqueous leach solution containing bromide ions is formed with HBr, NaBr or KBr. 
     
     
       5. Method according to claim 1, wherein the aqueous leach solution containing chloride ions is formed with a mixture of hydrochloric acid and sulphuric acid, the mixture containing at least 25% by weight of hydrochloric acid. 
     
     
       6. Method according to claim 1, wherein the aqueous leach solution also contains a source of sulphate ions. 
     
     
       7. Method according to claim 1, wherein the pH of the slurry is maintained between about 2.5 and 4.5 during the leaching reaction. 
     
     
       8. Method according to claim 1, wherein the leaching operation is carried out under an oxygen partial pressure of between about 200 and 300 psig. 
     
     
       9. Method according to claim 1, wherein the leaching operation is carried out for a period sufficient to effect at least 97% overall conversion of Cu. 
     
     
       10. Method according to claim 1, wherein the copper sulphide concentrates are essentially chalcopyrite concentrates. 
     
     
       11. Method according to claim 1, wherein the copper sulphide concentrates are dispersed in the leach solution in as-received condition, without prior grinding. 
     
     
       12. Method according to claim 1, wherein the copper sulphide concentrates are ground for one half hour prior to being dispersed in the leach solution. 
     
     
       13. Method according to claim 1, wherein upon separation of the leach residue, said residue is washed to eliminate remaining traces of chloride or bromide ions. 
     
     
       14. Method according to claim 1, wherein upon separation of the leach residue, the remaining leach solution is recycled and reused to form an aqueous leach solution suitable for treating fresh copper sulphide concentrates on a continuous, cyclic basis. 
     
     
       15. Method according to claim 1, wherein the copper values are recovered from the residue by selective dissolution of copper in an ammoniacal ammonium sulphate solution followed by solvent extraction from the ammoniacal liquor, stripping with sulphuric acid, and electrowinning from the sulphuric acid solution. 
     
     
       16. Method according to claim 1, wherein the copper values are recovered from the residue by leaching the residue in dilute sulphuric acid to dissolve the basic copper sulphate and electrowinning the copper values from the resulting solution. 
     
     
       17. Method according to claim 1 wherein initially no acid is present in the slurry. 
     
     
       18. A hydrometallurgical method of recovering copper values from copper sulphide concentrates, which comprises: a. forming an aqueous acid leach solution containing chloride or bromide ions therein;   b. adjusting the amount of total acid in the solution such that the molar ratio H +/Cu  is between about 0.15/1 and 0.65/1;   c. dispersing copper concentrates in said leach solution to form a slurry;   d. adjusting the amount of chloride or bromide ions in the slurry such that the molar ratio Cl -/Cu  or Br -/Cu  is greater than 0.08/1;   e. carrying out the leaching operation at a temperature between about 125° C. and 160° C. and under an oxygen partial pressure above 180 psig, while agitating the slurry;   f. separating resulting leach residue containing the copper values essentially in the form of basic copper sulphate from the leach solution; and   g. recovering the copper values from said leach residue.